I don't recall where I heard that, I may be mistaken. I'll keep looking around and update here when/if I find it again.

EDIT: Possibly http://www.nytimes.com/2013/06/11/us/how-edward-j-snowden-or... "Mr. Snowden has now turned over archives of “thousands” of documents, according to Mr. Greenwald, and “dozens” are newsworthy."